Approved advertisers receive a first look at the inventory of more than 120,000 Android apps, said Seth Socolow, SVP for strategic partnerships at Airpush.

“One of the main benefits [to AirX] is scale,” Socolow said. “We’ve got the second-largest mobile ad network on the Android platform [the largest is Google’s AdMob]. Another key benefit relates to the move towards hyperlocal programmatic buying: 50% of the traffic that we’re seeing through our exchange includes GPS lat/long information.”

OpenX launched its first private mobile ad exchange two years ago with Samsung. Partnering with Airpush on a new mobile private exchange “made sense” given its focus on location data, among other factors, said Rob Kramer, general manager of mobile at OpenX.

AirX offers only in-app banner ads and push notification ads as inventory, however Kramer said OpenX plans to offer rich media and video inventory through AirX later this year.

“We’ll start to see more mobile private exchanges as more buyers come and I think we’ll see a trend where private exchanges include specific data parameters, like location,” Kramer said.

Yet the demand for private mobile ad exchanges remains unclear. Mark Prior, VP of mobile at demand-side platform (DSP) and ad network Rocket Fuel, said only a few clients have shown interest in a mobile private exchange.

“The mobile exchanges that we work with have not been coming to us about getting access to a publisher through a private exchange [and] app media providers, like a game developer, are much more open to putting their inventory on the generally available exchange,” he explained.

Ajitpal Pannu, chief strategy officer at the mobile RTB exchange Smaato, agreed. “Private exchanges are used to create a demand for a limited supply and essentially drive up the value of CPMs,” Pannu said, “but the functionality and value varies by publisher and it’s not something we’re seeing a high demand for yet. ”

To participate on AirX, advertisers must pass the exchange’s white- and black-list filters, as well as any additional publisher controls, Kramer added. These controls are significant since industry insiders criticized OpenX’s quality control in 2012, when the RTB exchange was linked to sites that delivered botnet traffic. Since then, the company implemented additional controls, such as a manual review of all new publishers that enter its exchange and an automated filtering of suspect ad placements.

So far, a handful of advertisers representing auto manufacturers, auto dealerships, electronics companies, fast-food restaurants and political campaigns were given access to AirX several months ago as beta testers.

OpenX and Airpush face competition from other mobile ad exchanges like Nexage, which estimates 50% of its revenue will come from its mobile private exchange this year, up from 25% in 2013.